Ion exchange polyamine resins and method of preparing same



Patented June s, 1946 ION EXCHANGE POLYAMINE RESTNS AND METHOD OFPREPARING SAME solm'w. Eastes, Bel Air, Ma, assignor to The BesinousProducts a Chemical Company, Philadelphia, Pa., a corporation ofDelaware No Drawing. Application April 25, 1944, Serial No. 532,656

1 20 Claims.

This invention relates to nitrogenous resinous compositions which areparticularly useful for the absorption of acid-forming materials fromfluids. These compositions are characterized by their favorable capacityfor absorbing relatively large amounts of such acid-forming materialsand for doing so emcientlyupon regeneration and repeated use.

The present application is a continuation-inpart of my applicationSerial No. 387,688, filed April 9, 1941.

The properties of a resin having capacity for absorption of acid-formingmaterials should be such that along with high capacity and good basicitythere are physical properties which contribute to eficiency, freedomfrom contamination of the treated liquid or gas, ease of regenerationand washing, and long life on repeated use. A combination of suchproperties has been lacking in the materials heretofore proposed for theabsorption of acidic components in fluids.

More particularLv, this invention deals with nitrogenous resins whichare formed by the condensation of a phenol, formaldehyde, and analkposed, though insoluble in water, are soluble in dilute acids and inalkali hydroxide solutions. Obviously, these condensates do not meet therequirements for an anion exchange material. While it is known that manyresinous condensates become relatively insoluble when heated, mereheating of the condensates heretofore known does not-produce a materialhaving the balance of properties requisite for the type of resin 'herecontemplated as particularly useful mg phenol, an alkylene polyamine,and formaldehyde in an amount at least molecularly equivalent to bothphenol and amine to give a gel, and heating the gel under dryingconditions, for in- .stance, in an oven provided with vents, at a tern--perature above about C. but below the temperature at which "scorching"of the resulting resin would take place, that is, the temperature atwhich incipient decomposition occurs, resulting in loss of amino groups.The upper limit of temperature to which the condensate may be heatedvaries with the particular phenol and polyamine used and theirproportions, but, generally speaking, such upper limit is within therange of 135 to 150C. The preferredrange of temperature at which thecondensate may be heated under dryingconditions is C. to C. In anyevent, heating of the gel under drying conditions iscarried on at thechosen temperature for a period of time sufllcient to render theresulting resin insoluble in dflute strong acids, e. g., 5 to 10%sulfuric acid. Time of heating will vary inversely with the temperatureat which the heating is conducted. Within the preferred temperaturerange, the resin usually becomes insoluble in dilute strong acids withina period of from about thirty-six to about twelve hours.

Phenols which are useful in forming these resins include a wide varietyof aromatic compounds having one or more nuclear hydroxyl groups fromboth the monocyclic and polycyclic series. These phenols may containalkyl, cycloalkyl, aralkyl, aryl, alkoxy, aryloxy, droxyalkyl, nitro,halogeno, acyl, or other such substituents. Typical phenols are phenolitself, the cresols, the naphthols, phenyl phenol, benzyl phenol,cyclohexyl phehol, te1t.-butyl phenol, amyl phenol, octyl phenol,resorcinol, hydroquinone, catechol, guaiacol, natural tanning materialsof the catechol type, etc. These phenols all possess the common featurethat they have available for substitution hydrogen in the positionsortho and/or para to the phenolic hydroxyl group. They are commonlyknown as methylol-forming phenols. It is desirable thatthemethylol-forming phenol possess at leastv two, and preferably three,nuclear positions ortho or para to the phenolic hydroxyl group availablefor direct substitution per molecule.

The polyamines which are useful are then:- ylene polya nines suchasethylene diamine, diethylene triamine, triethylene tetramine,tetraethylene pentamine, N,N'-bis(aminopropyl)ethylene diamine,dipropylene triamine, tris(tri- 3 methylene) tetramine, and otherpolalkylene polyamines.

The formaldehyde may be used as an aqueous or organic solvent solution,as a gas, or as a solid polymer. Part of the formaldehyde may besupplied by compounds which yield methylene groups, such ashexamethylene tetramine.

The total mols of formaldehyde to be used are, as a rule, at least equalto the combined mols of the phenol and the polyamine. It is preferredthat the total mols of formaldehyde used be at least equal to the totalmols of polyamine plus 1.2 times the total mols of phenol. The amount offormaldehyde used, however, may be greater than the minima above stated.Beyond those amounts of formaldehyde which combine with the phenol andthe polyamine, excess formaldehyde will be driven off in the heatingoperation. The total amount of formaldehyde will depend not Only uponthe amounts of the other reactants but also upon the order of mixing thereactants and the conditions of the reaction. In general, sufficientformaldehyde should be added to ensure insolubility of the resins indilute strong acids, such as hydrochloric or sulfuric.

The proportions of the other reactants may also be widely varied. It hasbeen found that the capacity for absorption of acidic constituentsincreases with increasing proportions of amine, while hardness increaseswith increasing proportions of a phenol. Hardness i particularlyimportant when the temperature of fluids being treated is above that ofroom temperature. It is, therefore, desirable to hold the proportion ofpolyamine to phenol between four to one and one to four. A particularlysuitable ratio of polyamine to phenol is within the range of 2 to 1 molsof polyamine to l to 2 mols of phenol. A preferred ratio is one mol ofpolyamine per mol of phenol.

The three components of the reaction mixture may be combined in anydesired order to give resins having good capacity for the absorption ofacid-forming materials. The most effective methods of mixing are,however, to combine formaldehyde and a mixture of phenol and amine or tocombine amine with a mixture of phenol and formaldehyde. If formaldehydeand amine are mixed before the addition of a phenol, it is generallynecessary to use an additional amount of formaldehyde and control of thereaction is less certain. A large excess of formaldehyde, however, canbe avoided by supplying formaldehyde in two stages of the reaction. Animp r ant consideration is to effect reaction of all three componentsand to effect this reaction in such a way that a hydrophilic gel isfonned. This is accomplished by conducting the reaction in a solutioncontaining water, other solvents such as alcohol being permissible inconjunction therewith, mixing the reactants slowly and thoroughly andpreventing overheating of the mixture so that insoluble curds do notseparate. The rate of mixing, the temperatures of the various stages,and other precautions which are necessary to produce a gelatinousproduct vary somewhat from phenol to phenol, but should offer nodimculty in the light of what is said above.

Particularly desirable gel formation is ensured when the reactionmixture contains a strong hydroxide, such as sodium hydroxide, potassiumhydroxide, or trimethyl benzyl ammonium hydroxide. This may be addedbefore or during the condensation. Employment of a strong hydroxide isof substantial benefit when the phenol used is such that it does notreadily dissolve in an aqueous solution of the polyamine. Amounts ofstrong hydroxide up to a full mol per mol of phenol have been founduseful. However, the proportion of hydroxide to phenol may be widelyvaried. Proportions less than mol per mol have been found to actcyclically in making available for condensation even the phenols of lowsolubility.

After its formation, the hardened resin is rendered particularlysuitable for the absorption of acidic constituents from iluids bycrushing the hardened mass into particle form and screening to suitablemesh. Particle sizes of from 10 to 50 mesh have been found particularlydesirable for utilization in columns, for instance However,

larger and smaller particle sizes may be required for other applicationsto which the resin is adapted.

The products which are obtained by the procedure here described areresins of the phenolformaldehyde type which are chemicall orstructurally characterized by the presence of aminoalkylene aminomethylsubstituents on the phenyl nuclei. The alkylene chains of thesesubstituents may be interrupted by --NH groups to form alkylene chainsof at least two carbon atoms each between nitrogen atoms, thus formingpolyalkylene polyamine groups attached to phenyl nuclei throughmethylene groups. When polyethylene polyamines are used in the reaction,the resulting products contain polyethylene polyamine groups such astetraethylene pentamine, triethylene tetramine, or diethylene triaminegroups.

The following examples give more details regarding the preparation oftypical resinous compositions.

E'arample 1 A mixture was made by adding 47 parts of phenol t 216 parts(by weight) of aqueous 37% formaldehyde held at 29 C. by cooling. Thismixture was slowly added to 73 parts of triethylene tetramine, causingan immediate and vigorous reaction resulting in an increase oftemperature to almost C. and the formation of a gel, which wasmaintained at about 95 C. for an hour. The gel was then heated fortwentyfour hours in an oven at C., yielding 141 parts of a very hardresin. After it had been crushed to a 20/40 mesh size, washed with a 5%sodium carbonate solution and with water, and dried, it was tested forcapacity with an aqueous solution containing 400 parts per million ofsulfuric acid. It had a capacity of 279 milligrams per gram and gave anexcellent quality of performance, giving no color to the liquid treated,allowing free flow in columns, and permitting regeneration, washing andre-use at high efllciency.

Example 2 I Two hundred forty parts of aqueous 37% formaldehyde wascombined with a mixture of 46 parts of phenol and 95 parts oftetraethylene pentamine. Although a gel formed at once, the reactionmixture was heated on a steam bath for several hours, dried in an ovenat about 130 C., crushed to 20/40 mesh size, washed with a 3% ammoniasolution, and with water, and dried at low temperature with aircirculation. This resin is also of high capacity and gives anexcellent'performance on repeated use.

Example 3 A mixture of 58.5 parts of phenol and 243 parts of aqueous 37%formaldehyde was added to '73 parts of triethylene tetramine. The gelwhich formed was heated for an hour on a steam bath, dried at 115 C.,Washed with dilute sodium hydroxide solution, and then with water, anddried at 30-40 C. The resin thus prepared has a capacity of 253milligrams of sulfuric acid per gram of resin.

Example 4 Fifty-seven parts of dihydroxyphenyl dimethyl methane wasstirred into 150 parts of water to which eight parts of sodium hydroxidewas added. After most of the dihydroxyphenyl dimethyi methane haddissolved, 60 parts of aqueous 37% formaldehyde was added. The mixturewas stirred for about two hours with the temperature thereof held atabout 50 C. to give a clear solution. This was cooled to roomtemperature and there was then added 140 parts of tetraethylenepentamine while the reaction mixture was cooled to dissipate heat fromthe exothermic reaction. When this subsided, 102 parts of 37%formaldehyde was added and the temperature maintained at '7580 C. forseveral hours. There resulted a gel which was removed from the reactionvessel, dried at 115 C. for sixteen hours, crushed to 20/40 meshparticles, washed with a 5% sodium carbonate solution and with water,and air-dried. The resin is characterized by hardness, physicalstrength, and high capacity for anion exchange.

Example 5 Ninety parts of quebracho tannin and five parts of phenol weredissolved in 200 parts of water at 95 C. and 73 parts of triethylenetetramine added thereto, The resulting solution was cooled to 40 C.,whereupon 162 parts of aqueous 37% formaldehyde was added. An exothermicreaction took place, causing a rise in temperature to 60 C A gel soonformed. After the reaction mixture had been heated on a steam bath fortwo hours, the gel was removed from the reaction vessel, dried at 130 C.for sixteen hours, crushed, screened to a 20/40 mesh product, washedwith a 5% sodium carbonate solution and with water, and air-dried. Theresin has favorable physical properties and good capacity for anionexchange.

In the formation of these resins suitable for absorbing acid-formingmaterials, it is sometimes desirable, as has been indicated above, tocarry out the reaction in the presence of an alkali, such as sodiumhydroxide or potassium hydroxide. In other cases, the presence of anacid catalyzes the formation of a resin with the optimum balance ofproperties for anion exchange or for absorption of acidic materials. Theacid anions are removable from the hardened resinby treatment with asolution of an alkaline agent, such as soda ash. ammonia, sodiumhydroxide, etc. If desired, the resinous gel may be formed in thepresence of a filler or carrier, such as silica, alumina, starch, alphafloc, or the like, or inert fillers may be mixed with the gel or withthe resin.

By reaction of alkylene polyamine, a phenol,

and formaldehyde to form a gel-like condensate which is thereafterhardened under drying conditions at temperatures and times above setforth to form an insoluble resin, there are obtained compositions havinghigh capacity for anions and suitable properties for use in large scaleapparatus under repeated use. Such properties permit packing in columns,regeneration and washing, and good flow. I claim:

1. An anion exchange resin obtained by reacting in an aqueous medium,until a hydrophilic gel is formed, a. methylol-forming phenol, analkylene polyamine, and formaldehyde, in the proportions of one-fourthto four mols of polyamine per mol of phenol and of mols of formaldehydeat least equivalent to the total mols of phenol and polyamine, andthereafter heating said gel under drying conditions until a nitrogenousresin insoluble in dilute strong acids is formed, said heating beingconducted at a temperature above about 75 C. and below the scorchingtemperature of the resulting resin, whereby there results a resincharacterized by substantial hardness, high physical strength, goodabsorption capacity, and exceptional stability during use andregeneration.

2. An anion exchange resin obtained by react-- ing in an aqueous medium,until a. hydrophilic gel is formed, a methylol-forming phenol, analkylene polyamine, and formaldehyde, in the proportions of one-fourthto four mols of polyamine per mol of phenol and of mols of formaldehydeat least equivalent to the total mols of phenol and polyamine,thereafter heating said gel under drying conditions until a nitrogenousresin insoluble in dilute strong acids is formed, said heating beingconducted at a temperature above about 75 C. and below the scorchingtemperature of the resulting resin, and then breaking the resin intorelatively small particles, whereby there results a resin characterizedby substantial hardness, high physical strength, good absorptioncapacity, and exceptional stability during use and regeneration.

3. An anion exchange resin obtained by reacting in an aqueous medium andin the presence of a strong alkaline hydroxide, until a hydrophilic gelis formed, a methylol-forming phenol, an alkylene polyamine, andformaldehyde, in the proportions of one-fourth to four mols of polyamineper mol of phenol and of mols of formaldehyde at least equivalent to thetotal mols of phenol and polyamine, thereafter heating said gel underdrying conditions until a nitrogenous resin insoluble in dilute strongacids is formed, said heating being conducted at a temperature aboveabout 75 C. and below the scorching temperature of the resulting resin,and then breaking the resin into relatively small particles, wherebythere results a resin characterized by substantial hardness,

/ 4. An anion exchange resin obtained by reacting in an aqueous medium,until a hydrophilic gel is formed, a methylol-formin phenol, apolyalkylene polyamine, and formaldehyde, in the proportions of one-halfto two mols of polyamine per mol of phenol and of mols of formaldehydeat least equivalent to the mols of polyamine plus 1.2 times the mols ofphenol, and thereafter heating said gel under'drying conditions until anitrogenous resin insoluble in dilute strong acids is formed, saidheating being conducted at a temperature within the range of about C. toabout C., whereby there results a resin characterized by substantialhardness, high physical strength, good absorption capacity, andexceptional stability during use and regeneration.

- 5. An anion exchange resin obtained by reacting in an aqueous medium,until a. hydrophilic gel is formed, a metlwlol-formin phenol, apolyaikylene polyamine, and formaldehyde, in the proportions of one-halfto two mols oi polyamine per mol of phenol and of mols of formaldehydeat least equivalent to the mols of polyamine plus 1.2 times the mols ofphenol, thereafter heating said gel under drying conditions until anitrogenous resin insoluble in dilute strong acids is formed, saidheating being conducted at a temperature within the range of about 105C. to about 130 C., and then breaking the resin into relatively smallparticles, whereby there results a resin characterized by substantialhardness, high physical strength, good absorption capacity, andexceptional stability during use and regeneration.

6. An anion exchange resin obtained by reacting in an aqueous medium andin the presence of a strong alkaline hydroxide, until a hydrophilic gelis formed, a methylol-forming phenol, a polyalkylene polyamine, andformaldehyde, in the proportions of one-half to two mols of polyamineper mol of phenol and of mols of formaldehyde at least equivalent to themols of polyamine plus 1.2 times the mols of phenol, thereafter heatingsaid gel under drying conditions until a nitrogenous resin insoluble indilute strong acids is formed, said heating being conducted at atemperature within the range of about 105 C. to about 130 C., and thenbreaking the resin into relatively small particles, whereby thereresults a resin characterized by substantial hardness, high physicalstrength, good absorption capacity, and exceptional stability during useand regeneration.

7. An anion exchange material obtained by reactin in an aqueous mediumuntil a hydrophilic gel is formed a phenol having at least two nuclearhydrogen atoms per molecule in reactive positions available for directsubstitution, a polyalkylene polyamine, and formaldehyde, in theproportions of one-half to two mols of polyamine per mol of phenol andof mols of formaldehyde at least equivalent to the mols of polyamineplus 1.2 times the mols of phenol, and thereafter heating said gel underdrying conditions until a nitrogenous resin insoluble in dilute strongacids is formed, said heating being conducted at a temperature withinthe range of about 105 C. to about 130 0., whereby there results a resincharacterized by substantial hardness, high physical strength, goodabsorption capacity, and exceptional stability during use andregeneration.

8. An anion exchange resin obtained by reactin in an aqueous medium,until a hydrophilic gel is formed, a. methylol-forming phenol, apolyethylene polyamine, and formaldehyde, in the proportions of one-halfto two mols of polyamine per mol of phenol and of mols of formaldehydeat least equivalent to the mols of polyamine plus 1.2 times the mols ofphenol, and thereafter heating said gel under drying conditions until anitrogenous resin insoluble in dilute strong acids is formed, saidheating being conducted at a temperature within the range of about 105C. to about 130 0., whereby there results a resin characterized bysubstantial hardness, high physical strength, good absorption capacity,and exceptional stability during use and regeneration.

9. An anion exchange resin obtained by reacting in an aqueous medium,until a hydrophilic gel is formed, a methylol-forming phenol,tetraethylene pentamine, and formaldehyde, in the proportions ofone-half to two mols of pentamine per mol of phenol and of mols offormaldehyde at least equivalent to the mols of pentamine plus 8 1.2times the mols of phenol, and thereafter heating said gel under dryingconditions until a nitrogenous resin insoluble in dilute strong acidsis,

formed, said heating being conducted at a temperature within the rangeof about C. to about C., whereby there results a resin characterized bysubstantial hardness, high physical strength, good absorption capacity,and exceptional stability during use and regeneration.

10. An anion exchange resin obtained by reacting in an aqueous medium,until a hydrophilic gel is formed, a. methylol-forming phenol,triethylene tetramine, and formaldehyde, in the proportions of one-halfto two mols of tetramine per mol of phenol and of mols of formaldehydeat least equivalent to the mols of tetramine plus 1.2 times the mols ofphenol, and thereafter heatin said gel under drying conditions until anitrogenous resin insoluble in dilute strong acids is formed, saidheating being conducted at a temperature within the range of about 105C. to about 130 0., whereby there results a resin char acterized bysubstantial hardness, high physical strength, good absorption capacity,and exceptional stability during use and regeneration.

11. An anion exchange resin obtained by reacting in an aqueous medium,until a hydrophilic gel is formed, a methylol-forming phenol, diethylenetriamine, and formaldehyde, in the proportions of one-half to two molsof triamine per mol of phenol and of mols of formaldehyde at leastequivalent to the mols of triamine plus 1.2 times the mols of phenol,and thereafter heating said gel under drying conditions until anitrogenous resin insoluble in dilute strong acids is formed, saidheating being conducted at a temperature within the range of about 105C. to about 130 0., whereby there results a resin characterized bysubstantial hardness, high physical strength, good absorption capacity,and exceptional stability during use and regeneration.

12. An anion exchange material obtained by reacting in an aqueous mediumuntil a hydrophilic gel is formed a phenol having at least two nuclearhydrogen atoms per molecule in reactive positions available for directsubstitution, a polyethylene polyamine, and formaldehyde, in theproportions of one-half to two mols of polyamine per mol of phenol andof mols of formaldehyde at least equivalent to the mols of polyamineplus 1.2 times the mols of phenol, thereafter heating said gel underdrying conditions until a nitrogenous resin insoluble in dilute strongacids is formed, said heating being conducted at a temperature withinthe range of about 105 C. to about 130 C., and then breaking the resininto relatively small particles, whereby there results a resincharacterized by substantial hardness, high physical strength, goodabsorption capacity, and exceptional stability during use andregeneration.

13. An anion exchange resin obtained by reacting in an aqueous medium,until a hydrophilic gel is formed, phenol, a polyalkylene polyamine, andformaldehyde, in the proportions of one-half to two mols of polyamineper mol of phenol and of mols of formaldehyde at least equivalent to themols of polyamine plus 1.2 times the mols of phenol, and thereafterheating said gel underdrying conditions until a nitrogenous resininsoluble in dilute stron acids is formed, said heating being conductedat a temperature within the range of about 105 C. to about 130 0.,whereby there results a resin characterized by substantial hardness,high physical strength, good absorption capacity, and exceptionalstability during use and regeneration.

14. A method for preparing insoluble nitrogenous resinous compositionssuitable for absorbing acidic constituents from fluids which comprisesreacting in an aqueous medium, until a hydrophilic gel is formed, amethylol-forming phenol, an alkylene polyamine, and formaldehyde, in theproportions of one-fourth to four mols of polyamine per mol of phenoland of mols of formaldehyde at least equivalent to the total mols ofphenol and polyamine, and thereafter heating said gel under dryingconditions until a nitrogenous resin insoluble in dilute strong acids isformed, said heating being conducted at a temperature above about 75 C.and below the scorching temperature of the resulting resin, wherebythere results a resin characterized by substantial hardness, highphysical strength, good absorption capacity, and exceptional stabilityduring use and regeneration.

15. A method for preparing insoluble nitrogenous resinous compositionssuitable for absorb ing acidic constituents from fluids which comprisesreacting in an aqueous medium, until a hydrophilic gel is formed, amethylol-forming phenol, a polyalkylene polyamine, and formaldehyde, inthe proportions of one-half to two mols of polyamine per mol of phenoland of mols of formaldehyde at least equivalent to the mols of polyamineplus 1.2 times the mols of phenol, thereafter heating said gel underdryin conditions until a nitrogenous resin insoluble in dilute strongacids is formed, said heating being conducted at a temperature withinthe range of about 105 C. to about 130 C., and then breaking the resininto relatively small particles, whereby there results a resincharacterized by substantial hardness, high physical strength, goodabsorption capacity, and exceptional stability during use andregeneration.

16. A method for preparing insoluble nitrogenous resinous compositionssuitable for absorbing acidic constituents from fluids which comprisesreacting in an aqueous medium, until a hydrophilic gel is formed, aphenol having at least two nuclear hydrogen atoms per molecule inreactive positions available for direct substitution, a polyalkylenepolyamine, and formaldehyde, in the proportions of one-half to two molsof polyamine per mol of phenol and of mols of formaldehyde at leastequivalent to the mols of polyamine plus 1.2 times the mols of phenol,thereafter heating said gel under drying conditions until a nitrogenousresin insoluble in dilute strong acids is formed, said heating beingconducted at a temperature within the range of about 105 C. to about 130C., and then breaking the resin into relatively small particles, wherebythere results a resin characterized by substantial hardness, highphysical strength, good absorption capacity, and exceptional stabilityduring use and regeneration.

17. A method for preparing insoluble nitrogenous resinous compositionssuitable for absorbing acidic constituents from fluids which comprisesreacting in an aqueous medium and in the presence of a strong alkalinehy roxide, until a hydrophilic gel is formed, a m thylol-forming phenol,a polyethylene polyamine, and formaldehyde, in the proportions ofone-half to two mols of polyamine per mol of phenol and of mols offormaldehyde at least equivalent to the mols of polyamine plus 1.2 timesthe mols of phenol, thereafter heating said gel under drying conditionsuntil a nitrogenous resin insoluble in dilute strong acids is formed,said heating being conducted at a temperature within the range of about105 C. to about 130 C., and then breaking the resin into relativelysmall particles.

18. A method for preparing insoluble nitrogenous resinous compositionssuitable for absorbing acidic constituents from fluids which com-.

prises reacting in an aqueous medium, until a non-resinous, formed, a,methylol-forming phenol and. formaldehyde, reacting therewith, until ahydrophilic gel is formed, an alkylene polyamine and more formaldehyde,the proportions of polyamine and phenol used being within the range ofone-fourth to four mols of the former per mol of the latter, the totalmols of formaldehyde used being at least equivalent to the mols of bothphenol and polyamine, and thereafter heating said gel under dryingconditions until a nitrogenous resin insoluble in dilute strong acids isformed, said heating being conducted at a temperature above about C. andbelow the scorching temperature of the resulting resin, whereby thereresults a resin characterized by substantial hardness, high physicalstrongth, good absorption capacity, and exceptional stability during useand regeneration.

19. A method for preparing insoluble nitrogenous resinous compositionssuitable for absorbing acidic constituents from fluids which comprisesreacting in an aqueous medium and in the presence of a strong alkalinehydroxide, until a non-resinous, soluble methylol compound is formed, amethylol-forming phenol and formaldehyde, reacting therewith, until ahydrophilic gel is formed, an alkylene polyamine and more formaldehyde,the proportions of polyamine to phenol used being within the range ofone-half.

to two mols of the former per mol of the latter, the total mols offormaldehyde used being at least equivalent to the mols of polyamineplus 1.2 times the mols of phenol, thereafter heating said gel withinthe temperature range of about C. to about C. under drying conditionsuntil a nitrogenous resin insoluble in dilute strong acids is formed,and then breaking the resin into relatively small particles.

20. A method for preparing insoluble nitrogenous resinous compositionssuitable for absorbing acidic constituents from fluids which comprisesreacting in an aqueous medium and in the presence of a strong alkalinehydroxide, until a non-resinous, soluble methylol compound is formed,phenol and formaldehyde, reacting therewith, until a hydrophilic gel isformed, an alkylene polyamine and more formaldehyde, the proportions ofpolyamine to phenol used being within the range of one-half to two moleof the former per mol of the latter, the total mols of formaldehyde usedbeing at least equivalent to the mols of polyamine plus 1.2 times themols of phenol, thereafter heating said gel within the temperature rangeof aboutpiii? C. to about 130 C. under drying conditions until anitrogenous resin insoluble in dilute strong acids is formed. and thenbreakingthe resin into relatively small particles.

JOHN W. EASTES.

soluble methylol compound is

